On a hot July morning in 2001, Korey Stringer, a 27-year-old Pro Bowl offensive tackle for the Minnesota Vikings, walked onto the team’s training camp field in Mankato, Minnesota. He would never leave the hospital alive.
Stringer’s death was not simply a tragedy for his wife, Kelci, his young family and his parents. It became a defining case in the legal and medical examination of exertional heat stroke in professional sport. More than two decades later, the circumstances surrounding his death continue to influence the way athletes are protected from extreme heat.
Stringer turned up to training camp on July 29, 2001. During the first day of practice, he complained of stomach problems and subsequently vomited during training. The next morning he returned to practice. After completing the session, he became seriously ill and was taken to an air-conditioned medical trailer. His condition deteriorated.
According to the Minnesota Supreme Court’s account of the case, Stringer’s temperature was not measured until he reached hospital. It was 108.8 degrees Fahrenheit. He was unconscious, his pulse was 148 beats per minute and his blood pressure could not be obtained. Hospital staff attempted aggressive cooling and other emergency treatments, but Stringer died at approximately 1:50 a.m. on August 1 from complications of heat stroke.
The subsequent litigation would raise fundamental questions about whether String’s death could have been prevented.
A Family’s Search for Answers
Kelci Stringer, his widow and the personal representative of his estate, brought a wrongful-death action. The litigation alleged failures in the care and treatment provided to Stringer before his hospitalization. The family’s claims also extended into questions concerning the NFL’s policies, training conditions and the heat-retaining characteristics of football equipment.
The Minnesota proceedings included claims against members of the Vikings’ medical and training staff. Seven expert affidavits were submitted on the care and treatment Stringer received. According to the Minnesota Court of Appeals, those experts generally criticized the failure to properly investigate his condition, prevent his participation in practice, recognize changes in his behavior, monitor vital signs, diagnose and treat heat stroke and rapidly obtain emergency medical treatment.
The litigation did not produce a simple courtroom narrative of liability. Claims against individual team employees were affected by Minnesota’s workers’ compensation and co-employee immunity rules, and the Minnesota Supreme Court ultimately held that the relevant employees did not owe Stringer the personal duty alleged by the estate.
Separate federal litigation was brought against the NFL and equipment manufacturers and the federal case included allegations that Stringer had been expected to practice in extreme heat while wearing heat-retaining equipment and without adequate acclimatization, supervision or medical care. The litigation ultimately resulted in settlements, including a settlement with Riddell concerning its helmet and shoulder pads.
But for the expert witness community, one figure stands out.
Dr Douglas Casa
Expert witness, Dr Douglas J. Casa was a professor of kinesiology at the University of Connecticut when he became involved in the Stringer litigation. He worked with Kelci Stringer for years as an expert witness. UConn records state that he served as an expert witness in the case for approximately eight years.
His qualifications were unusually well aligned with the central medical question. Casa holds a bachelor’s degree in biology from Allegheny College, a master’s degree in athletic training from the University of Florida and a doctorate in exercise physiology from the University of Connecticut. He is a Board of Trustees Distinguished Professor of Kinesiology at UConn and chief executive officer of the Korey Stringer Institute. He has published hundreds of peer-reviewed papers and book chapters and has presented extensively on exertional heat stroke, heat illness, hydration and prevention of sudden death in sport.
His clinical experience is equally relevant. UConn reports that Casa has treated hundreds of cases of exertional heat stroke without a fatality. He is also a fellow of the American College of Sports Medicine, the National Athletic Trainers’ Association and the National Academy of Kinesiology.
Of importance, Casa’s expertise was not merely academic. It encompassed research, clinical treatment and the practical management of heat emergencies.
The Important Issue: Cool First
Casa’s testimony and subsequent commentary have repeatedly focused on one deceptively straightforward principle: rapid cooling is the critical intervention in exertional heat stroke.
In 2026, reflecting on his experience as an expert witness, Casa said: “I’ve been an expert witness in 85 court cases of people dying from heat stroke, and in every single one the person didn’t need to die if they were properly treated and cooled.”
He added: “With a $150 tub of ice and water, these people would still be alive.”
His conclusion is stark because it translates a highly technical medical issue into something readily understood by a jury: when exertional heat stroke is suspected, the priority is immediate cooling rather than allowing transportation logistics to delay treatment.
Casa has also explained the particular significance of Stringer’s case. “If Korey had gone in a cold immersion tub, we would not be chatting right now,” he said. “He would’ve had dinner with his teammates that night.”
These observations illustrate the distinctive role of an expert witness. The expert does not decide liability. That remains the function of the court or jury. Instead, the expert supplies specialized knowledge that permits the fact-finder to understand whether conduct was consistent with accepted medical principles and whether an alternative intervention might have materially altered the outcome.
From Litigation to Legacy
There is a remarkable final chapter to the Stringer family’s ordeal.
Kelci Stringer’s legal battle helped lead to the creation of the Korey Stringer Institute at the University of Connecticut in 2010. Casa became its founding scientific figure and continues as its chief executive officer. The institute’s purpose is to prevent sudden death in sport, with exertional heat stroke at the center of its work.
The legacy is now visible on football practice fields across America. Cold-water immersion tubs and emergency action plans have become central components of heat-illness preparedness. The NFL’s enhanced heat-safety protocols are part of a much broader transformation in sports medicine that followed Stringer’s death.
For Kelci Stringer and the wider family, however, no subsequent safety protocol could erase what happened. Their legal struggle began with an unbearable personal loss: a young husband, father and professional athlete dying after a training session that should have ended like countless others.
For expert witnesses, the case offers a powerful reminder of the responsibility attached to specialist evidence. Casa’s contribution went beyond identifying heat stroke. His work helped explain what happens when the body’s temperature rises beyond its ability to regulate itself, why rapid cooling matters and how a medical emergency that can be survivable can become fatal when treatment is delayed.
Stringer’s death changed professional sport. The litigation changed the conversation about responsibility. And the expert evidence helped turn one family’s tragedy into a body of knowledge intended to ensure that other athletes do not suffer the same fate.
by Edward Price
